Jitladda Wasinrat

Optimization of the table speed of lower extremity CT angiography protocols in different patient age groups

BACKGROUND Scanning with 64-slice multidetector row CT (MDCT) is usually faster than blood flow in peripheral arteries of the lower extremities, and the distal arteries of lower extremities are difficult to visualize, particularly in elderly patients. Thus, the optimal table speed for CT angiography (CTA) studies should be adjusted for appropriate patient age groups. OBJECTIVE We evaluated the relative efficacy of different table speeds in several age groups of patients with suspected peripheral arterial occlusive disease (PAOD) undergoing CTA of lower extremity arteries, as a guideline for routine use. METHODS This retrospective study reviewed routine CTA of the lower extremity arteries of 107 patients with suspected PAOD to evaluate vascular opacification in each vascular segment of 5 age groups: < or =40 years (group 1), 41-60 years (group 2), 61-70 years (group 3), 71-75 years (group 4), and > or =76 years (group 5). Adequate vascular opacification was measured for attenuation in the suprarenal and infrarenal abdominal aorta and in the arteries of the lower extremity. Venous contamination was also measured. RESULTS Adequate vascular opacification from the suprarenal aorta to the level of the mid-popliteal artery was shown in all patients. Arterial opacification at the dorsalis pedis or plantar arteries was visualized in 85.7%-91.7% of patients and at the plantar arch arteries in 84.1%-91.7%. Minimal venous contamination was also shown adjacent to arterial enhancement, ranging from 0% to 28.6%. CONCLUSION Performing CTA of the lower extremities with 64-slice MDCT could reduce the table speed to allow adequate arterial opacification and minimal venous contamination.

64-Slice MDCT Angiography of Upper Extremity in Assessment of Native Hemodialysis Access

Objective: To compare multidetector row computed tomographic (MDCT) angiography with conventional digital subtraction angiography (DSA) in the evaluation of vascular access stenoses in hemodialysis patients. Materials and methods: Twenty-one consecutive patients were imaged with MDCT angiography and subsequent DSA. The superficial vein of leg was used as the route for intravenous administration. The vascular stenosis was assessed in not significant (<50% stenosis), moderate stenosis (50%-74% stenosis), severe stenosis (75%-99%), and total occlusion (100%). The accuracy, sensitivity, specificity, positive, and negative predictive values were calculated for significant vascular stenosis using DSA as the standard reference. Results: The sensitivity and specificity of MDCT angiography for the detection of significant hemodialysis vascular access were 100% (95% CI, 89.3%-100%) and 94.8% (95% CI, 89.1%-97.6%), respectively. The positive and negative predictive values were 84.2% (95% CI, 68.1%-93.4%) and 100% (95% CI, 95.8%-100%), respectively. The accuracy of MDCT angiography for detection of significant stenoses was 95.9% (95% CI, 91.4%-97.0%). Conclusions: MDCT angiography provides excellent correlation in vascular stenosis as compared with DSA in hemodialysis access. Complete assessment of entire vascular segments could be performing with MDCT angiography in planning before endovascular intervention or surgical correction.

Computed Tomography of Aortic Intramural Hematoma and Thrombosed Dissection

A retrospective study was undertaken to evaluate the appearance of the aortic wall on computed tomography for the purpose of developing criteria for differentiating acute aortic intramural hematoma from thrombosed false lumen seen in aortic dissection. Computed tomography angiography findings of the thoracoabdominal aorta in 23 patients with suspected intramural hematoma and 25 with thrombosed false lumen were reviewed. The more common features of an intramural hematoma were hyperattenuation of the aortic wall, wall thickness less than a quarter of the aortic diameter, intrinsic wall calcification, a lesion extending around the entire aortic circumference, and ulcer-like projections that may be precursors of intramural hematoma. Wall thickness less than a quarter of the aortic diameter, lesion extending around the entire aortic circumference, and ulcer-like projections were the most useful indicators for distinguishing intramural hematoma from the thrombosed false lumen in aortic dissection.

A 53-year-old woman with progressive headaches.

A 53-year-old woman presented with a 1-month history of severe headache and intractable vomiting. Physical examination revealed left facial palsy and generalized weakness of the extremities (grade IV/V all extremities) without other localizing signs. She had no known underlying disease and there was no significant family history. MRI of the brain disclosed multiple ill-defined high signal lesions in T2W at left lower pons, left thalamus, subcortical regions of temporal, parietal, and frontal lobes bilaterally, and periventricular white matter. Nodular enhancement was noted in the left frontal lobe lesion (Figure 1a), left thalamus (not shown) and left pons (Figure 1b). Irregular leptomeningeal enhancement was also noted diffusely. The largest mass present at the left frontal lobe was 2 cm in largest dimension and showed marked peritumoral vasogenic edema (Figure 1a). High resolution chest CT revealed an ill-defined mass at the posterior basal segment of the right lower lobe, 3.2 cm in greatest dimension (not shown). There were also multiple small nodules involving both lungs, ranging from 0.4 to 0.5 cm. Stereotactic biopsy of the left frontal lobe lesion was performed. MICROSCOPIC PATHOLOGY